The Effect of Annealing on the Thermal Properties of RIM Urethane Elastomers

Abstract

Reaction Injection Molded (RIM) polyurethane elastomers are receiving a good deal of attention from the automobile industry. In recent papers by Liedtke1 at General Motors Manufacturing and Development, Mikulec2 at Ford PDAO and Lloyd3 at Texaco, it has become apparent that RIM polyurethane elastomers are a leading candidate for making automobile exterior body panels. One very important performance property in this end use is thermal dimensional stability. This is so for two reasons: first, paint bake cycles tend to involve relatively high temperatures, around 280–350°F and second, in use temperatures are often rather high for long periods of time. A part made from a RIM polyurethane elastomer should be able to withstand these conditions without an unacceptable degree of distortion.